TD-SCDMA, the abbreviation for “Time Division-Synchronous Code Division Multiple Access” (also abbreviated as TD), is the first complete mobile communication standard developed by China communication industries ever since.
As a proprietary intellectual property of China, TD-SCDMA incorporates the advantages of Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) together. Therefore, TD-SCDMA coexists with the WCDMA standard in Europe and the CDMA2000 standard in the United States as the mainstream 3G mobile communication standards.
A TD-SCDMA/GSM dual-mode mobile phone can operate in both a single-mode mode and a dual-mode mode.
In the single-mode mode, connection to the network can be accomplished according to a current standard, for example, according to TD in a TD only mode or according to GSM in a GSM only mode. In the dual-mode mode, the mobile phone operates in a TD preference mode; i.e., TD is preferentially adopted for network connection.
When dialing up to a website www in the TD preference mode, it is required that no switching is made when there is a 3G signal; and when strength of the 3G signal is too low, the GPRS will be disconnected and then it is allowed to switch to a 2G network. Then, when the user dials up to the website www again in the dual-mode mode, the system will firstly determine whether it is currently in a 3G network. If it is currently not in a 3G network, then the system will compulsively log on the 3G network; and if it fails to log on the 3G network, it means that the process of dialing up to the website www fails and an indication of “the 3G signal is weak or there is no 3G network” is given.
As can be known from the above descriptions, when the mobile phone in the dual-mode mode is not in a 3G network or when the 3G signal is weak, the mobile phone that has been switched to a 2G network must firstly try to log on the 3G network when re-initiating the network business. This makes the network searching time too long, which is very inconvenient for the user.